I agree with the original poster's comments about ignoring them and having them fade out of existance. Unfortunately, many citizens haven't figured this out yet.
We have to face the fact that here in America where the Supreme Court has mandated that no restrictions on content can be placed on this type of speech (unless content supression will insure that no imminent lawless action will take place, and is the least restrictive way to do so), that the only way we have to get rid of groups that hold such views is to ignore them until they fade away.